Hi In this case, the vacuum might work against you. You change the pressure outside the package and you get a flex. Flex translates to dimensional changes. That gives you a frequency shift. People make absolute pressure sensors this way :) Rb’s are by no means the only frequency standard impacted by this effect. Precision OCXO’s have the same issue.
If you had enough room inside the package, you could do a “can in a can” sort of approach. The outer vacuum sealed can flexes. The inner vacuum sealed can does not see anything. You don’t eliminate the sensitivity this way, you do attenuate it quite a bit with each layer. The question then becomes - is is worth the increase in size? Since the pressure sensitivity is well below many other environmental factors …. probably not. Bob > On Mar 22, 2017, at 1:04 AM, jimlux <jim...@earthlink.net> wrote: > > On 3/21/17 4:29 PM, Hal Murray wrote: >> >> scmcgr...@gmail.com said: >>> However CSAC not subject to barometric effects as Rb units are >> >> Does anybody tried to measure CSAC vs pressure? >> >> >> > The physics package in a CSAC is a vacuum, so it probably won't make much > difference. > > But, as a practical matter, I have a system with a CSAC going through thermal > vacuum testing as I write this. We'll get some test data and we can compare > the frequency against GPS and a OCXO at room temp/pressure, and at various > temps in vacuum. > > Remind me in 2 weeks, and I should have the data plotted. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
